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Message-ID: <17e02cd8-eba1-91b8-2506-91a7893ac967@amd.com>
Date: Wed, 27 Jul 2022 12:04:10 -0400
From: Felix Kuehling <felix.kuehling@....com>
To: Yu Zhe <yuzhe@...china.com>, alexander.deucher@....com,
christian.koenig@....com, Xinhui.Pan@....com, airlied@...ux.ie,
daniel@...ll.ch
Cc: amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
liqiong@...china.com
Subject: Re: [PATCH] drm/amdkfd: use time_is_before_jiffies(a + b) to replace
"jiffies - a > b"
This patch introduces a build warning for me:
CC [M] drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.o
In file included from /home/fkuehlin/compute/kernel/include/linux/spinlock.h:54,
from /home/fkuehlin/compute/kernel/include/linux/mmzone.h:8,
from /home/fkuehlin/compute/kernel/include/linux/gfp.h:6,
from /home/fkuehlin/compute/kernel/include/linux/slab.h:15,
from /home/fkuehlin/compute/kernel/drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.c:44:
/home/fkuehlin/compute/kernel/drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.c: In function ?interrupt_wq?:
/home/fkuehlin/compute/kernel/include/linux/typecheck.h:12:18: warning: comparison of distinct pointer types lacks a cast
12 | (void)(&__dummy == &__dummy2); \
| ^~
/home/fkuehlin/compute/kernel/include/linux/jiffies.h:106:3: note: in expansion of macro ?typecheck?
106 | typecheck(unsigned long, b) && \
| ^~~~~~~~~
/home/fkuehlin/compute/kernel/include/linux/jiffies.h:154:35: note: in expansion of macro ?time_after?
154 | #define time_is_before_jiffies(a) time_after(jiffies, a)
| ^~~~~~~~~~
/home/fkuehlin/compute/kernel/drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.c:159:7: note: in expansion of macro ?time_is_before_jiffies?
159 | if (time_is_before_jiffies(start_jiffies + HZ)) {
| ^~~~~~~~~~~~~~~~~~~~~~
I think you need to change the the definition of start_jiffies to be
unsigned long. Do you want to submit a v2 of your patch?
That said, I think the existing code was fine, though the type-mismatch
highlighted by your patch is a bit iffy.
Regards,
Felix
Am 2022-07-26 um 22:59 schrieb Yu Zhe:
> time_is_before_jiffies deals with timer wrapping correctly.
>
> Signed-off-by: Yu Zhe <yuzhe@...china.com>
> ---
> drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> index a9466d154395..6397926e059c 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> @@ -156,7 +156,7 @@ static void interrupt_wq(struct work_struct *work)
> while (dequeue_ih_ring_entry(dev, ih_ring_entry)) {
> dev->device_info.event_interrupt_class->interrupt_wq(dev,
> ih_ring_entry);
> - if (jiffies - start_jiffies > HZ) {
> + if (time_is_before_jiffies(start_jiffies + HZ)) {
> /* If we spent more than a second processing signals,
> * reschedule the worker to avoid soft-lockup warnings
> */
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